s="bboobbobobbobbbbobboobnbobobbotbobbw"
b=0
o=0
bob=0
for char in s:

    if char=="b":
        b=1
    if char=="o" and b==1:
        o+=1
    if char=="o" and b==1 and o!=1:
        b=0
        o=0
    if char=="b" and o==1:
        bob+=1
        b=1
        o=0
    if char!="b" and char!="o":
        b=0
        o=0




print('Number of times bob occurs is: '+str(bob))